Participants were asked to recall everything they ate or drank over the course of 48 hours, every three to 10 days.

Professor An calculated the amount of plain water each person consumed as a percentage of their daily dietary water intake from food and beverages combined.

Beverages such as unsweetened black tea, herbal tea and coffee were not counted as sources of plain water, but their water content was included in An’s calculations of participants’ total dietary water consumption.

On average, participants consumed about 4.2 cups of plain water on a daily basis, accounting for slightly more than 30% of their total dietary water intake.

Participants’ average calorie intake was 2,157 calories, including 125 calories from sugar-sweetened beverages and 432 calories from foods such as desserts, pastries and snacks.

A small but statistically significant 1% increase in participants’ daily consumption of plain water was associated with a decrease in calorie intake, as well as slight reductions in participants’ consumption of fat, sugar, sodium and cholesterol.

While Professor An found that the decreases were greater among men and among young and middle-aged adults, he suggested they could have been associated with these groups’ higher daily calorie intakes.